On August 17, 2016, the FDA issued an emergency authorization to InBios International to sell a test that is supposed to detect IgM antibodies to the Zika virus (see figure below).

This is a digitally-colorized transmission electron micrograph (TEM) of Zika virus, which is a member of the family Flaviviridae. Virus particles, here colored blue, are 40 nm in diameter, with an outer envelope, and an inner dense core.

The test has been offered commercially by LabCorp. However, now, a mere 4 months after issuing emergency authorization for use of the test, the FDA has issued the following safety warning:ZIKV Detect IgM Capture ELISA by InBios International, Inc: FDA Safety Communication - Wait for Confirmatory Test Results Before Making Patient Management Decisions.The FDA is alerting physicians who care for pregnant women meeting CDC Zika virus clinical criteria and/or CDC Zika virus epidemiological criteria, that the U.S. commercial testing facility, Laboratory Corporation of America (LabCorp), has reported some false positive results from the ZIKV Detect test. Because confirmation tests may take a week to a month to complete, the FDA is issuing this alert so that health care providers and patients know about a higher likelihood of false positive results.RECOMMENDATIONS: The FDA urges health care providers to be aware that:

Positive IgM Zika virus results are only presumptive for the detection of antibodies to Zika virus.

The confirmatory testing may take a week to a month to be performed, but can be prioritized if CDC is aware that the sample is from a pregnant woman. Laboratories should be notified of the patient’s pregnancy status.